3.4 Question D Weigh the risks
identified in A), B) and C) against the reduction of
mercury emissions
from coal-based power plants due to the lower electricity
consumption of CFLs compared to conventional household lamps.
Incorporate and consider the potential health risks from mercury
when CFLs are broken, accidentally in the household or after
disposal, into the life cycle analysis of CFLs, taking into
account the reduction of human health and environment risks
resulting from the potential reduction in mercury emissions from
coal-based power plants and the reduction of the emission of
other pollutants due to the lower electricity consumption of
CFLs compared to conventional household lamps.

In A, B, C, the SCHER
concluded that the environmental risks of Hg due to the use of
CFLs are very low. The VITO (2009) report demonstrated that the
amount of Hg emitted over a CFL lifetime per lumen is
approximately 10% lower than that of conventional CLS bulbs
(Table 2). Considering that this normalized life cycle
estimation (per lumen per hour) includes both the Hg emissions
from the use and disposal phase, the net emission reduction
would be in that order of magnitude, if all conventional
household lamps were replaced by CLFs. It is noted that halogen
lamps emit even less Hg (up to 39% less) per lumen per
hour.

The SCHER would like to
point out, that weighing risks to different targets (human
health and ecosystems) from
different outputs (Hg and
greenhouse gases) from
different products (various kinds of light bulbs) presents some
considerable challenges that are only just now being addressed
in risk assessment. Hence, SCHER is only able to give a partial
and somewhat tentative response to this question.

That said, from an environmental perspective, the weighing of
the adverse effects of
mercury emissions on
ecosystems and the
climate effects of greenhouse
gas emissions is made easier by virtue of the mercury
emissions per lumen per hour being roughly similar across lamp
types (see Table 2). On the other hand the environmental impacts
of the CFLi lamps is considerably less than the rest, Thus the
VITO (2009) report presents data per lumen per hour for each
environmental indicator including two main environmental impact
indicators, i.e. total energy consumption (GER) and total global
warming potential (GWP). These indicators for CFLi lamps are
about 25% of those of GLS-C and GLS-F lamps. Compared to HL-MV-
LW, HL-MV-HW and HL-LV lamps, CFLis have 13%, 53% and 22% less
impact on the GER indicator and 13, 47 and 25% less impact on
the GWP indicator, respectively.

The SCHER is therefore
of the opinion that CFLis offer a net environmental benefit as
compared with the other light bulbs considered. This could have
been more equivocal had the Hg released from disposal caused the
life cycle emissions from the CFLis to exceed that of the other
light bulbs. And it is more equivocal in weighing the
environmental gains from CFLis with any risks to human lives
from accidental exposures. Often, weighing different effects
across different targets is based on expert judgements. Another
approach is to weigh different effects on the basis of public
values and with a common monetary measure. Thus, the variations
per lumen per hour across light bulb types would be modulated as
follows: for greenhouse
gases with the social cost of carbon; for human health
with values for life and/or healthy life years; for
ecosystems with the
values of ecosystem
services. That would put all the risks in the same monetary
units.

SCHER counsels some
caution with this kind of approach but is of the opinion that
for the sake of developing transparent assessment that properly
informs management and policy the above-described approach to
risk-benefit analysis needs to be given more critical attention.
For example, without this kind of approach, it would not be
possible at this stage for SCHER to give an opinion that weighs
the benefits from greenhouse
gas reductions with any increased risks of accidental
exposure for human health. That has to remain a matter for
judgement in the risk management process.